Project 4

For a vehicle of gross weight 300 kg, the motor ratings are 1200Wh, 65V. The range is 225km and the maximum speed is 60kmph. Calculate the capacity of the battery pack required and the number of series-parallel connections. Give a stepwise discussion on how a battery pack is built.
Note: Choose any relevant lithium ion datasheet

Ans:

Calculation of battery pack capacity:

Considering : LIR18650 2600mAh battery data sheet

No.of series parallel cell calculation:

Series connection	Voltage rating
motor voltage	65V
cell nominal voltage	3.7V
no.of series connection	65/3.7=17.56=18
Parallel connection	Current rating
motor current	18.6A
cell current	1.3A
no.of parallel connection	18.6/1.3=14.3=15
Total cell required	18*15=270

Construction process of battery:

Step 1:Collecting raw material:Batteries are a crucial requirement for electric vehicles .batteries require eight key raw materials including manganese , nickel , cobalt , copper , aluminium , graphite and titanium ,We got these raw material from mining.

Step2: Manufacturing of anode and cathode,Two important parts of any cell are the anode and the cathode.The cathode is a metal that is combined, naturally or in the laboratory, with oxygen,the combination is called an oxide.The anode is a metal that would oxidize if it were allowed to and, other things being equal, is more likely to oxidize than the metal that forms part of the cathode.

The third substance into which the anode and the cathode are placed is called an electrolyte. In many cases this material is a chemical combination that has the property of being alkaline. Thus, an alkaline battery is one that makes use of an alkaline electrolyte. A cell will not produce electricity by itself unless it is placed in a circuit that has been rendered complete by a simple switch, or by some other switching connection in the appliance using the battery.

Step3:Assembling the battery module:

Usually all electrodes except cathode is assembled first,then power coating process is followed by assembling of cathode and anode.Cathode sheet and anode sheet will punch be punched and stacked into pouch which will be folded with separator,During lithium ion battery assembling process,first of all positive electrode is stacked on negative electrode then pressed several times until electrode materials are firmly contact with each other and then electrolyte solution is applied all over electrodes to prevent oxidation of metal surface of anode and conductivity also get improved,after this heat sealing is used to weld both ends of cathode cavity on aluminium foil at bottom of lithium ion battery pack to seal out atmosphere from inside.Because exposure to air or water may affect capacity of battery when being used later.Positive electrode plate, negative electrode plate, separator and plastic backing late from a sealed cavity without any contact with outside atmosphere which can maintain sufficient voltage when installed later. After batteries are heat sealed, ifneeded, electrical test devices can be connected to electric terminals. Then pressurized gas charging starts. Pressure must reach twice as much as pressure during normal working process while charging time must not exceed 30 hours or cycle life of battery will decrease rapidly. Charging pressure depends on kind of materials used in electrode products but there’s no explicit regulation about it in official standards so that manufactures tend to use lower than its standard pressure when making Lithium-Ion batteries.

Step4:cell testing,after assembling the cell the cell undergoes varies testing method to assure its performance examples of cell testing are life cycle test,capacity fade test,calender test,dynamic load test

Step5:Inter connecting cell,Spot welding:In spot welding a very short pulse of high current pass through twopiees of metal to melt together and form a solid connection ,nickel cell bars are used for cylindrical interconnection ,th

Step6:Assembling the battery pack,In this a battery pack is assembled by using inter connected cells as shown in below figure and connecting terminals are made in the battery pack

Step7:BMS is provoided in battery systems,battery management system monitors,protects and allow the user to use the battery pack in a safe manner,BMs implemented in printed circuit board mounted with the batterypack

Green portion is the BMS and cell are connected in series and parallel,it is for the safety operator and and also protect the cell,it helps to improve the life of battery pack,It sense voltage,current,temperature and also provide different parameter to the user.

Step8:When the battery pack is ready battery pack undergoes various testing to assure it quality and performance that is safety test like short circuit test over charge test nail penetration test,mechanical test like shock test vibration test and water proof test.